Flight operation indicator



NOV 2, 1948- J. wElssENBAcH FLIGHT OPERATION INDICATOR Filed March 29, 1946 RW a( 5 ya ATTORNEYS Patentecl Nov. 2, 1948 UNITED STATES PATENT OFFICE 25452621 FL'IGHTJOPERATION' INDCA-Toa" Js'eph'Weissen-hach, Los Angeles, Calif. ApplicatonrvMarchZS.'1946}Serial No. 658,190-

(Granted under the act of March V3, 1883, as amended April 30, 1928; 370 O. G. 757) 4 Claims.`

The Ainvention described herein maybe manu'- factured and used by or for the Government for governmental `purposes without payment to me of any royalty thereon.

The present invention'relates to a novel flight operation indicator for aircraft in which Yvisual indication of the proper airspe'ed for conducting various ilight operations under conditions of varying'gross weights are given directly in relation to the indicated airspeed.

The various flight performance criteria-sucih-as airspeed to fly at various gross weights to obtain maximum endurance, minimum airspeed for take-off with various gross weights, etc., are currentlyfincluded in tables appended to the night operation manuals furnished with the airplane, but are Vinconvenient for'pilots to use particularly where yno pre-computed flight plan has been made.

In accordance with the present' invention a plurality of 'indicators are provided cooperating with the dial of an airspeed indicator. The indicators are respectively set by a setting knob which also operates a gross Weight scale which moves relative to a' stationary pointer. When the Y gross weight scale indicia is set opposite the reference index or pointer indicating the present gross weight of the airplane, the various 4indicators are automatically set to indicate the respective airspeeds 'for selected flight operation conditions. By maintaining the airspeed at the desired value the airspeed indicator pointer will overlie or be in alignment 'with the indicator corresponding to the desired iight condition and deviations ther`efrom will be readily Visually apparent. By knowing the initial gross weight and approximate pow-` er output requirements the fuel consumption and hence the change in gross weight may be readily computed and the indicators reset from timeV to time =to correspond to the existing gross weight.

It is, therefore, an object oi the inventionl to provide, in conjunction with an airspeed indicator, auxiliary indicators cooperating with the airspeedindicator dialto indicate various ilight'performa-nce criteria in terms of airspeed, a separate settable' pointer and pointer and gross weight' scale and pointer and a common setting means forradiustably setting the Vgross weight scale and the auxiliary indicators. f

Other objects and features of the invention will become apparent by reference to the detailed de# scription hereinafter given and to the appendedv drawin'gsin which:

Fig. 1 is a graphical illustration of the varia tion in airspeed of Acertainilight operation-'criteria with variationin gross weight 'of awell-kown four-engine cargo airplane which illustrate the design basis of an instrument inaccordance with the invention, and y Fig. 2 illustrates in front elevation an' airspeed indicator incorporating the invention', and l Fig. 3 is an exploded perspective View illustrating the manner of construction and operation of the gross Weight and auxiliary or ight'condition indicators.

Referring to Fig. 1, Whichis a characteristic speed 'chart for a four-engine cargo airplane having a normal gross weight varying between 35 and '73 thousand pounds, the chart illustrates the variation in're'commended operatingT airspee'd i'or threeflight operating conditions. ,The Acurve indicatedby'reference character A indicates the variationin recommended airspeed for take-ofi and climb-out with wing flaps set 20 down and alsoindicates normal iinal approach speed with ilaps setV at 40 down and further represents the stalling speed with Wingilaps up and power oiT, as the' gross weight varies. It is seen from curve A that climb-out airspeed should vary from 83 MjP; Hffor agross weight of 40,000 lbs.'to v112 M. P. I-I. for a gross weight of 73,000 lbs. Curve B represents the variation in recommended air? speed tofobtain maximum endurance and varies between M. P. H. and 142 M. P H. for a gross weight change above indicated. Curve (C indicates the variation in recommended airspeedfor maximum range as varying from to 178 M. P. H. for the gross Weight variation above noted. While curve C is not a straight line, a straight line variation may be assumedwithsmall error. While `the performance curves Bland Cv will vary with altitude there will be one altitude most practical -for range andv endurance and curves for this altitude will be the most suited for the purposesof the invention.

The manner in which the invention is vcarried out will beapparent by reference to Figs.r2 `and 3. As lseenin these figures the reference numeral l indicates the'case of a conventional airspeed indicator adapted to be actuated by differential' pressure when-connected to a conventional Pitotstatic airspe'ed indicator head (not shown).

The airspeed indicator l has a uniformly di vided 'airsp'eed dial 2 which cooperatesfwith a pointerS actuated by /a Vpointer shaft '4 -whichisrOtated by the differential pressure responsive mechanism (not shown. The pointer 3 indicates relative -to the `airspeed indicia on'dial 2 the instant lvalue of the airspeed during flight. Anfarcu'ate opening i5 is provided-'inthe dial-2 and- Referring to Fig. 3 the indicator tabs I3 and I1 are seen to be bent over portions oi arms Ill, I i and i3 respectively, which are integral with sector gears I I, I5 and I9 which mesh with pinion gears I2, It and respectively. The pinions l2, I6 and 20 are rigidly secured to an actuating or setting shaft 22 adapted to be manually rotated by means of reduction gears 23 and 2li, the latter being actuated by a setting knob 25 positioned in front of the instrument casing. Thel arcuate plate 'i carrying the gross weight indicia 6 is provided with gear teeth 26 which mesh with a further pinion gear 21, also rigidly mounted on shaft 22 to rotate therewith. The sector gears Il, I5 and I9 and indicator plate 'I are each provided with hub bores 28 so that they may be rotatably supported on a hollow pivot stud 29 supported from the rear face oi dial 2 and through which the pointer shaft 4 extends for independent operation by the airspeed indicator mechanism.

If the angular extent of the gross weight scale on plate 'I is such as to cover 90 for a range of `gross weights of from say 40,000 to 73,000 lbs., then indicator I'l which indicates variation in climb-out airspeed (curve A of Fig. 1) should rotate over the airspeed indicator scale indicia from 83 M. P. H. to 112 M. P. H., or approximately 26. The ratio between pinion 20 and sector gear I9 is, therefore, selected to give the proper speed reduction. The ratio between gears I5, I5 and il, I2 respectively, are arranged such that indicator I 3 corresponding to curve B, Fig. 1, moves over the airspeed indicia from 105 to 142 M. P, H., or 33, and indicator 9 corresponding to curve C moves from 135 to 178 M. P. I-I., or 39", for same angular movement of the gross weight indicator scale.

The indicator tabs 9, I3 and I'l are each painted a distinctive color and a legend strip is aixed to the aircraft instrument board giving the interpretation of the indication of the auxiliary indicators.

Operation The pilot prior to starting a flight determines the gross weight of the airplane from the load schedule and rotates knob 25 until the starting gross weight indicia of say thousand pounds appears opposite index 3 in window 5 of the airspeed indicator` dial, indicator I'I should then be at 102 M. P. H. indicating the safe take-01T and climb-out airspeed for this Weight and during take-off the airspeed pointer should be opposite indicator Il. Indicator I3 should be at the 130 M. P, H. indicia to indicate the airspeed for maximum endurance at the existing gross weight and similarly indicator 9 should indicate 162 M. P. H. as the airspeed for long range. Knowing the engine power output the fuel consumption in gallons and pounds per hour may be determined and the new gross weight computed at various times during the flight and the instrument reset accordingly and the airspeed indicator pointer kept opposite the selected auxiliary indicator. At the end of the flight, indicator I3 will approximately indicate the safe maneuvering ap- .proach airspeed with aps set at 20 down and indicator Il will indicate the normal final approach speed with flaps at 40 down and will also indicate the stalling speed with naps up and power oi. It is thus apparent that indicating means are provided to enable the pilot to determine the desired performance criteria and by keeping the airspeed pointer opposite the respective indicators can safely takew, fly a mission at airspeeds to maintain maximum endurance or range and can make a safe approach and let down at the point of landing.

It will be understood that each instrument will be suitable only for a specific type airplane but the only diierence from type to type will be the variation in gear ratios for the various auxiliary pointers. Where the performance curves of the type shown in Fig. 1 vary considerably from straight lines, compensating cams may be employed for actuating the auxiliary indicators to indicate airspeeds in a non-linear manner as a function of gross weight and other flight conditions than those illustrated in Fig. l may be represented by additional indicators.

While one form of the invention has :seen illustrated and described, other modifications and variations therein will become apparent to those skilled in the art as coming within the scope of the invention as dened in the appended claims.

I claim:

1. An instrument for indicating the desired airspeed for eicient flight operation ci an aircraft for varying gross weight conditions, comprising an airspeed indicator having a dial with airspeed indicia thereon and a pointer movable thereover, a plurality of auxiliary indicators movable about the pointer axis and cooperating respectively with the indicia on said dial to indicate the desired airspeeds for diiferent flight conditions under variable gross weight conditions, a scale calibrated in terms of gross weight, an inn dicator cooperating therewith said scale and indicator being relatively movable for setting to indicate the existing gross weight of the aircraft,

tothe desired eflicient airspeed for the selected flight condition.

2. The structure as claimed in claim 1, in which thel respective auxiliary indicators and the gross weight scale are operatively connected to the setting means by gearing such that the angular movement of the respective auxiliary indicators respectively bear a fixed relation to the angular movement of the gross weight scale.

f. 3. The combination with an airspeed indicator having an airspeed dial and cooperating pointer, an auxiliary indicator movable relative to the dial and cooperating with the pointer to indicate the attainment of a desired airspeed for a definite ight operation condition, which desired airspeed les .as a function of the gross weight of the irplane, a gross weight indicating means for `*visually indicating the gross weight of the air- -fplane and manual setting means for simultanefously actuating the auxiliary indicator and the 'gross weight indicating means such that the movement of the auxiliary pointer between prel. determined points relative to the airspeed dial is 5 in a predetermined ratio to the indication of the gross Weight indicating means.

4. In an airspeed indicator having a dial with airspeed graduations and a cooperating pointer adapted to indicate the instant value of airspeed, auxiliary indicators respectively movable ovei` zones of the airspeed dial graduations such that coincidence of the pointer with the respective auxiliary indicators indicates that the instant airspeed corresponds to the desired airspeed for a selected iiight performance condition, a gross weight indicating means settable for indicating the gross Weight of the aircraft, gearing interconnecting the auxiliary indicators and the gross weight indicating means such that the settings oi the auxiliary indicators bear a functional relation to the setting of the gross Weight indicating means, and manual means for actuating the gearing- JOSEPH WE-ISSENBACH.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,023,825 Urfer Dec. 10, 1935 2,137,194 Weber Nov. 15, 1938 2,152,635 Crane et a1. Apr. 4, 1939 2,258,826 Torkelson Oct. 14, 1941 

